Backflow preventer assembly

ABSTRACT

A backflow preventer assembly includes a housing having a first end and a second end, a first mounting assembly configured to removably secure a first check valve at a region of first end of the housing, and a second mounting assembly configured to removably secure a second check valve at a region of the second end of the housing. The housing includes a wall having an inner surface defining a through bore extending between the first and second ends. Each mounting assembly has a wall with an inner surface defining a through bore in fluid communication with the housing through bore. A first coupling secures the first mounting assembly to the housing, and a second coupling secures the second mounting assembly to the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.09/093,678, filed on Jun. 9, 1998, entitled “Backflow PreventerAssembly,” now U.S. Pat. No. 6,021,805, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

This invention relates to a backflow preventer.

Backflow preventers are principally used for preventing contamination ofa public water distribution system by preventing backflow orback-siphonage of contaminated water into the system. Usually, thebackflow preventer assembly is installed in a pipeline between a mainsupply line and a service line that feeds an installation, e.g., hotels,factories or other institutions, or even a multi or single familyresidence. A backflow preventer assembly typically includes two checkvalves permitting flow only in the direction from the main supply lineto the service line.

SUMMARY OF THE INVENTION

In one aspect, the invention features a backflow preventer assemblyincluding a housing having a first end and a second end, a firstmounting assembly configured to removably secure a first check valveadjacent the first end of the housing, and a second mounting assemblyconfigured to removably secure a second check valve adjacent the secondend of the housing. The housing includes a wall having an inner surfacedefining a through bore extending between the first end and the secondend. Each mounting assembly has a wall with an inner surface defining athrough bore in fluid communication with the housing through bore. Afirst coupling secures the first mounting assembly to the housing, and asecond coupling secures the second mounting assembly to the housing.

Embodiments of this aspect of the invention may include one or more ofthe following features.

The first and second couplings are solder joints, weld joints, orclamps. Alternatively, the first coupling includes threads on the innersurface of the housing wall adjacent the first end of the housing andthreads on an outer surface of the first mounting assembly, and thesecond coupling includes threads on the inner surface of the housingwall adjacent the second end of the housing and threads on an outersurface of the second mounting assembly.

In another illustrated embodiment, the first coupling includes a flangeon the first mounting assembly and a flange at the first end of thehousing for coupling to the first mounting assembly flange, and thesecond coupling includes a flange on the second mounting assembly and aflange at the second end of the housing for coupling to the secondmounting assembly flange. Alternatively, the first coupling includes acircumferential groove on the first mounting assembly and acircumferential ridge at the first end of the housing wall, and thesecond coupling includes a circumferential groove on the second mountingassembly and a circumferential ridge at the second end of the housingwall.

The backflow preventer assembly further includes plating materiallocated on the inner surface of the housing and the inner surface of thefirst mounting assembly. The plating material is a metal coating, e.g.,nickel, or a polymer coating, e.g., polyurethane.

The backflow preventer assembly further includes a first ball valveassembly attached to the first mounting assembly and a second ball valveassembly attached to the second mounting assembly. The first mountingassembly and the second mounting assembly each includes an inner end andan outer end. The outer ends of the first mounting assembly and thesecond mounting assembly are threaded, and the first ball valve assemblyis threadedly attached to the outer end of the first mounting assemblyand the second ball valve assembly is threadedly attached to the outerend of the second mounting assembly.

An outer surface of the housing wall, an outer surface of the firstmounting assembly wall, an outer surface of the first ball valveassembly, an outer surface of the second mounting assembly wall, and anouter surface of the second ball valve assembly include platingmaterial. An inner surface of the first ball valve assembly and an innersurface of the second ball valve assembly include plating material.

The backflow preventer assembly further includes a first check valveassembly attached to the first mounting assembly and a second checkvalve assembly attached to the second mounting assembly. The firstmounting assembly and the second mounting assembly each includes aninner end and an outer end. The inner ends of the first mountingassembly and the second mounting assembly are threaded, and the firstcheck valve assembly is threadedly attached to the inner end of thefirst mounting assembly and the second check valve assembly isthreadedly attached to the inner end of the second mounting assembly.

The housing wall defines an access port, and a cover closes the accessport. The backflow preventer assembly includes a plurality of testcocks.

A pressure reduction assembly is in fluid communication with the housingthrough bore, and a connection assembly secured to the housing wallattaches the pressure reduction assembly to the backflow preventer. Theconnection assembly includes a union nut. The housing wall includes anoutward extension for attachment of the pressure reduction assemblythereto. The outward extension defines a through bore.

In another aspect, the invention features a backflow preventer assemblyincluding a housing having a first end and a second end, a wall havingan inner surface defining a through bore extending between the first endand the second end, and a connection assembly. The housing wall includesan outward extension defining a through bore in fluid communication withthe housing through bore, and the connection assembly is secured to theoutward extension for attachment of a pressure reduction assemblythereto. The connection assembly includes a union nut and a cylindricaltube. The cylindrical tube has a first end axially inserted into thethrough bore of the outward extension and a second end with a rimconfigured to retain the union nut.

In another aspect, the invention features a method of mounting ballvalves and check valves to a backflow preventer. The method includessecuring opposed surfaces of a first mounting assembly and a housingwith securing material, and securing opposed surfaces of a secondmounting assembly and the housing.

Embodiments of this aspect of the invention may include one or more ofthe following features.

An inner surface of the housing, an inner surface of the first mountingassembly, and an inner surface of the second mounting assembly areplated with plating material. The plating material forms a wallrestricting migration of the securing material into a bore of thehousing, a bore of the first mounting assembly, and a bore of the secondmounting assembly.

The method further includes threadedly attaching ball valve assembliesto the outer ends of the first and second mounting assemblies, andthreadedly attaching check valve assemblies to the inner ends of thefirst and second mounting assemblies.

In another aspect, the invention features a method of mounting valves toa backflow preventer including securing opposed surfaces of a firstmounting assembly and a first end of a housing, securing opposedsurfaces of a second mounting assembly and a second end of the housing,removably attaching a first check valve assembly to an inner end of thefirst mounting assembly, and removably attaching a second check valveassembly to an inner end of the second mounting assembly.

Embodiments of this aspect of the invention may include one or more ofthe following features.

The method further includes removably attaching first and second ballvalve assemblies to the outer ends of the mounting assemblies. Theopposed surfaces of the mounting assemblies and the housing are securedtogether with securing material. The mounting assemblies and the housingare threaded, bolted, clamped, or crimped together. The check valveassemblies are threadedly attached to the mounting assemblies, and theball valve assemblies are threadedly attached to the mountingassemblies.

The method further includes plating an inner surface of the housing, aninner surface of the first mounting assembly, and an inner surface ofthe second mounting assembly with plating material.

Advantages of the invention include a backflow preventer assembly thatis less expensive to manufacture than currently available backflowpreventer assemblies for similar applications, and permits easy serviceand replacement of the check valves and ball valves.

Other features and advantages of the invention will become apparent fromthe following detailed description and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a somewhat diagrammatic cross-sectional view of a backflowpreventer assembly according to the invention;

FIG. 2 is a somewhat diagrammatic cross-sectional view of the backflowpreventer assembly of FIG. 1 shown with check valves and a coverremoved;

FIGS. 3A-3D are somewhat diagrammatic partial cross-sectional views ofthe backflow preventer assembly of FIG. 2 with alternative methods forsecuring valve mounts to the assembly housing;

FIG. 4 is a somewhat diagrammatic cross-sectional view of a reducedpressure backflow preventer assembly; and

FIG. 5 is an exploded side view of the pressure reduction assembly ofFIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a backflow preventer assembly 10 includes a housing20 having a first end 22, a second end 24, and a wall 25. A through bore30 extends between ends 22, 24 of housing 20 for flow of watertherethrough. A pair of valve modules 40, 50 are located in the regionsof ends 22, 24, respectively, of housing 20.

Valve module 40 includes a mount 43, a ball valve assembly 60, e.g.,Ball Valve Assembly Part No. FBV-E-775 available from Watts Industries,North Andover, Mass., and a check valve assembly 80, e.g., Check ValveAssembly Part No. SA-775CA37 also available from Watts Industries. Athrough bore 48 defined by mount 43 and ball valve assembly 60 is influid communication with housing bore 30 when check valve assembly 80 isin an open, flow position. Mount 43 has an outer end 42, an inner end44, and a wall 45 having an outer surface 47 and an inner surface 46.Inner end 44 of mount 43 steps down in outer diameter at a shoulder 44 ato define a contact surface 32. To secure mount 43 to housing 20, innerend 44 of mount 43 is inserted into first end 22 of housing 20, withcontact surface 32 abutting an inner surface 26 of housing 20. Securingmaterial 34, e.g., solder or hard solder (brazing), is used to connectcontact surface 32 to inner surface 26 of wall 25. Alternatively,contact surface 32 and inner surface 26 are welded together.

Outer end 42 of mount 43 defines external threads 222. Ball valveassembly 60 defines cooperating internal threads 242 for connecting ballvalve assembly 60 to mount 43. An o-ring 243 is located between mount 43and ball valve assembly 60 to prevent fluid leakage therebetween. Innerend 44 of mount 43 defines internal threads 224. Check valve assembly 80defines cooperating external threads 225 for connecting check valveassembly 80 to mount 43. An o-ring 260 is located between mount 43 andcheck valve assembly 80 to prevent fluid leakage therebetween.

Valve module 50 includes a mount 53, a ball valve assembly 70, e.g.,Ball Valve Assembly Part No. FBV-775 also available from WattsIndustries, and a check valve assembly 90, e.g., Check Valve AssemblyPart No. SA-775CB37 also available from Watts Industries. A through bore58 defined by mount 53 and ball valve assembly 70 is in fluidcommunication with bore 30 when check valve assembly 90 is in an open,flow position. Mount 53 has an outer end 52, an inner end 54, and a wall55 having an outer surface 57 and an inner surface 56. Inner end 54 ofmount 53 steps down in diameter at a shoulder 54 a to define a contactsurface 36. To secure mount 53 to housing 20, inner end 54 of mount 53is inserted into first end 22 of housing 20, with contact surface 36abutting inner surface 26 of housing 20. Securing material 38, e.g.,solder or hard solder (brazing), is used to connect contact surface 36to inner surface 26 of wall 25. Alternatively, contact surface 36 andinner surface 26 are welded together.

Outer end 52 of mount 53 defines external threads 232. Ball valveassembly 70 defines cooperating internal threads 252 for connecting ballvalve assembly 70 to mount 43. An o-ring 253 is located between mount 43and ball valve assembly 70 to prevent fluid leakage therebetween. Innerend 54 of mount 53 defines internal threads 234. Check valve assembly 90defines cooperating external threads 235 for connecting check valveassembly 90 to mount 43. An o-ring 270 is located between mount 43 andcheck valve assembly 90 to prevent fluid leakage therebetween.

Housing 20 defines a port 28 which provides access to bore 30 and checkvalve assemblies 80, 90. A lip 29 of housing 20 defines a region 301(FIG. 2) for retaining fastening nuts 302 having an inner threaded bore306. Port 28 is closed by securing a cover 27 to housing 20 withthreaded fastening screws 300 which are received by nuts 302. Acircumferential rim 31 of cover 27 defines a groove 303 in cover 27 inwhich an o-ring 305, e.g., made from Viton, is located to create afluid-tight seal between cover 27 and lip 29.

Referring to FIG. 2, an assembly of mounts 43, 53, housing 20, and ballvalve assemblies 60, 80 is plated. Inner surface 26 of housing 20, innersurface 46 of mount 43, inner surface 56 of mount 53, inner surface 76of ball valve assembly 60, and inner 77 of ball valve assembly 80 areplated with, e.g., nickel or chrome, to form an inner wall 500. Ballvalve assemblies 60, 80 are held in their open positions during theplating process, e.g., electroless nickel plating. Wall 500 acts to sealand restrict migration of securing material 34, 38 into bores 30, 48,and 58.

Plating material is also applied to an outer surface 26 a of housing 20,to outer surfaces 47, 57 of mounts 43, 53, respectively, and to outersurfaces 47 a, 57 a of ball valve assemblies 60, 70, respectively, toform an outer wall 501. Wall 501 acts to seal and restrict migration ofsecuring material 34, 38. Walls 500, 501 also function to minimizeoxidation of backflow preventer assembly 10 and to assist in sealingsmall leaks. In general, the plating material can be made from materialsthat are corrosion resistant, e.g., metal coatings and polymer coatings.Examples of metal and polymer coatings include, but are not limited to,nickel, chrome, teflon, epoxy, and polyurethane.

Valve mounts 43, 53 can also be secured to the housing by methods otherthan soldering and welding. For example, referring to FIG. 3A, a valvemount 53 a includes threads 48 a on an outer surface 36 a of the mountfor engaging threads 46 a on an inner surface 26 a of housing 20 a.Referring to FIGS. 3B-3D, in other embodiments, a mount 53 b is securedto a housing 20 b with a clamp 51 b (FIG. 3B); a mount 53 c is attachedto a housing 20 c by securing a flange 43 c of mount 53 c to a flange 44c of housing 20 c, e.g., with bolts 42 c, (FIG. 3C); and a mount 53 d issecured to housing 20 d by crimping housing 20 d to createcircumferential grooves 40 d, 41 d in housing 20 d and mount 53 d,respectively (FIG. 3D).

Referring again to FIG. 1, check valve assemblies 80, 90 can be accessedfor service and replacement through port 28. To remove a non-functioningcheck valve assembly, cover 27 is unscrewed from housing 20 and thecheck valve assembly is disengaged from its respective mount (43 or 53).A new or rebuilt check valve assembly is then inserted into back flowpreventer assembly 10 through port 28 and engaged with the respectivemount.

Check valve assemblies 80, 90 are oriented in sequence to allow flow ofwater through bore 30 in a first direction, indicated by arrow, F (FIG.1), but to prevent back flow of water in the opposite direction. Checkvalve modules 80, 90 are biased in the opposite direction of arrow, F,to exceed a predetermined threshold before the check valves are opened.

In use, potable water from the public water distribution system entersthe backflow preventer assembly 10 at an end 42a of ball valve assembly60. Assuming that ball valve assemblies 60, 70 are open and that thesupply pressure exceeds the predetermined threshold value biasing thecheck valve assemblies 80, 90 towards closed positions, the check valveassemblies open to allow water flow in through first end 42 a of ballvalve assembly 60, through bores 48, 30 and 58, and finally through anend 52 a of ball valve assembly 70. In the closed position, ball valveassemblies 60, 70 are used to isolate backflow preventer assembly 10from external water flow for either servicing check valve assemblies 80,90, as described above, or testing water quality and pressure through aseries of test ports 100, 110, 120, 130.

In an alternative embodiment shown in FIGS. 4 and 5, a reduced pressurebackflow preventer assembly 200 includes a pressure reduction assembly210 for relieving excess pressure. Backflow preventer assembly 200includes a housing 202 having a tubular extension 205 and a connectionassembly 226 mounted to tubular extension 205 for attaching pressurereduction assembly 210 to housing 202.

Connection assembly 226 includes a tube 228 attached to tubularextension 205 and an union nut 230 having threads 233 for engagingpressure reduction assembly 210. Tube 228 has a flared edge 229′ at end229, and union nut 230 has an inwardly flared edge 232′ configured toengage tube edge 229′. To assemble connection assembly 226 to housing202, union nut 230 is first slid over end 227 of tube 228, and then tube228 is joined, such as by solder, weld, crimp, clamp, flange, orthreads, to tubular extension 205. The abutment of edge 232′ againstedge 229′ retains union nut 230 on tube 228.

Pressure reduction assembly 210 includes a body 215, a cover 310attached to body 215, e.g., by a circumferential nut 330, and a hose508. Body 215 defines an inlet bore 220, an inlet bore 250, and anoutlet bore 290. Hose 508 has an inlet end 506 located at the upstreamside of valve module 600 and an outlet end 505 threadedly attached tocover 310 and in fluid communication with inlet 250. Cover 310 defines apassage 400 for flow of fluid from hose 508 to inlet 250.

Body 215 includes threads 217 at inlet 250 and threads 223 at inlet 220,as best seen in FIG. 5. Threads 223 at inlet 220 engage with union nut230 of connecting assembly 226 to secure pressure reduction assembly 210to housing 202, and threads 217 at inlet 250 engage circumferential nut330 to secure cover 310 to body 215.

Body 215 defines a central through bore 280. Removably mounted withinthrough bore 280 is a relief valve 311. Relief valve 311 includes avalve element 315 movable between an open position (as shown in FIG. 4)permitting fluid flow from hose 508 to inlet 250, and a closed positionin which passage 400 is blocked to limit flow from hose 508 to inlet250. Relief valve 311 includes a spring 308 which biases valve element315 toward the closed position. Valve element 315 has a seal 410 whichengages a face 412 of cover 310 to block passage 400 when in the closedposition.

Relief valve 311 includes an end seal assembly 404 located in outlet290. Assembly 404 defines a through bore 308 and valve element 315 has astem 401 located within through bore 307 having a sealing surface 307′for blocking outlet 290 when valve element 315 is in the open position.When valve element 315 is in the closed position, sealing surface 307′is removed from through bore 307 allowing fluid communication betweeninlet 220 and outlet 290. Cover 310 has recess 420 and valve element 315has an extension 430 located within recess 420 for guiding valve element315 during movement of valve element 315 between the open and closedpositions.

During normal operation, fluid at inlet 506 travels through hose 508 toinlet 250. The fluid pressure causes valve element 315 to move towardits open position, blocking outlet 290. When the fluid pressure at inlet506 drops below a predetermined value, spring 308 moves valve element315 toward the closed position. This permits any fluid locateddownstream of valve module 600, e.g., in a central bore 510 of housing202, to exit 200 by traveling through inlet 220 and out of pressurereduction assembly 210 via outlet 290. Thus, if valve 550 fails, anybackflow of fluid exits backflow preventer assembly 200 through pressurereduction assembly 210.

Other embodiments are within the scope of the following claims.

What is claimed is:
 1. A backflow preventer assembly comprising: ahousing having a first end and a second end, the housing including awall having an inner surface defining a through bore extending betweenthe first end and the second end, the wall defining an access port, afirst mounting assembly including a wall having an inner surfacedefining a through bore in fluid communication with the housing throughbore adjacent the first end of the housing, the first mounting assemblyinner surface being configured to removably secure a first check valvethereto, the first mounting assembly including a test port, a secondmounting assembly including a wall having an inner surface defining athrough bore in fluid communication with the housing through boreadjacent the second end of the housing, the second mounting assemblyinner surface being configured to removably secure a second check valvethereto, the second mounting assembly including a test port, a firstcoupling for securing the first mounting assembly to the housing, and asecond coupling for securing the second mounting assembly to thehousing.
 2. The backflow preventer assembly of claim 1 wherein the firstcoupling comprises a solder joint.
 3. The backflow preventer assembly ofclaim 2 wherein the second coupling comprises a solder joint.
 4. Thebackflow preventer assembly of claim 1 wherein the first couplingcomprises a weld joint.
 5. The backflow preventer assembly of claim 4wherein the second coupling comprises a weld joint.
 6. The backflowpreventer assembly of claim 1 wherein the first coupling comprisesthreads on the inner surface of the housing wall at the first end of thehousing and threads on an outer surface of the first mounting assembly.7. The backflow preventer assembly of claim 6 wherein the secondcoupling comprises threads on the inner surface of the housing wall atthe second end of the housing and threads on an outer surface of thesecond mounting assembly.
 8. The backflow preventer assembly of claim 1wherein at least the first coupling comprises a clamp.
 9. The backflowpreventer assembly of claim 8 wherein the second coupling comprises aclamp.
 10. The backflow preventer assembly of claim 1 wherein the firstcoupling comprises a flange on the first mounting assembly and a flangeat the first end of the housing for coupling to the first mountingassembly flange.
 11. The backflow preventer assembly of claim 10 whereinthe second coupling comprises a flange on the second mounting assemblyand a flange at the second end of the housing for coupling to the secondmounting assembly flange.
 12. The backflow preventer assembly of claim 1wherein the first coupling comprises a circumferential groove on thefirst mounting assembly and a circumferential ridge at the first end ofthe housing wall.
 13. The backflow preventer assembly of claim 12wherein the second coupling comprises a circumferential groove on thesecond mounting assembly and a circumferential ridge at the second endof the housing wall.
 14. The backflow preventer assembly of claim 1further comprising plating material located on the inner surface of thehousing and the inner surface of the first mounting assembly.
 15. Thebackflow preventer assembly of claim 14 wherein the plating materialcomprises a metal coating.
 16. The backflow preventer assembly of claim15 wherein the metal coating comprises nickel.
 17. The backflowpreventer assembly of claim 14 wherein the plating material comprises apolymer coating.
 18. The backflow preventer assembly of claim 17 whereinthe polymer coating comprises polyurethane.
 19. The backflow preventerassembly of claim 1 further comprising a first ball valve assemblyattached to the first mounting assembly and a second ball valve assemblyattached to the second mounting assembly.
 20. The backflow preventerassembly of claim 19 wherein the first mounting assembly and the secondmounting assembly each includes an inner end and an outer end, the outerends of the first mounting assembly and the second mounting assemblybeing threaded, the first ball valve assembly being threadedly attachedto the outer end of the first mounting assembly and the second ballvalve assembly being threadedly attached to the outer end of the secondmounting assembly.
 21. The backflow preventer assembly of claim 20wherein an outer surface of the housing wall, an outer surface of thefirst mounting assembly wall, an outer surface of the first ball valveassembly, an outer surface of the second mounting assembly wall, and anouter surface of the second ball valve assembly include platingmaterial.
 22. The backflow preventer assembly of claim 21 wherein aninner surface of the first ball valve assembly and an inner surface ofthe second ball valve assembly include plating material.
 23. Thebackflow preventer assembly of claim 1 further comprising a first checkvalve assembly attached to the first mounting assembly and a secondcheck valve assembly attached to the second mounting assembly.
 24. Thebackflow preventer assembly of claim 23 wherein the first mountingassembly and the second mounting assembly each includes an inner end andan outer end, the inner ends of the first mounting assembly and thesecond mounting assembly being threaded, the first check valve assemblybeing threadedly attached to the inner end of the first mountingassembly and the second check valve assembly being threadedly attachedto the inner end of the second mounting assembly.
 25. The backflowpreventer assembly of claim 1 further comprising a cover for closing theaccess port.
 26. The backflow preventer assembly of claim 1 furthercomprising a pressure reduction assembly in fluid communication with thehousing through bore.
 27. The backflow preventer assembly of claim 26further comprising a connection assembly secured to the housing wall forattaching the pressure reduction assembly to the backflow preventer. 28.The backflow preventer assembly of claim 27 wherein the connectionassembly comprises a union nut.
 29. The backflow preventer assembly ofclaim 26 wherein the housing wall includes an outward extension forattachment of the pressure reduction assembly thereto, the outwardextension defining a through bore.
 30. A backflow preventer assemblycomprising: a housing having a first end and a second end, the housingincluding a wall having an inner surface defining a through boreextending between the first end and the second end, the wall defining anaccess port, a first mounting assembly including a wall having an innersurface defining a through bore in fluid communication with the housingthrough bore adjacent the first end of the housing, the first mountingassembly having an inner end and an outer end, a second mountingassembly including a wall having an inner surface defining a throughbore in fluid communication with the housing through bore adjacent thesecond end of the housing, the second mounting assembly having an innerend and an outer end, a first coupling for securing the first mountingassembly to the housing, a second coupling for securing the secondmounting assembly to the housing, a first check valve assembly removablyattached to the inner end of the first mounting assembly, a second checkvalve assembly removably attached to the inner end of the secondmounting assembly, a first ball valve assembly removably attached to theouter end of the first mounting assembly, and a second ball valveassembly removably attached to the outer end of the second mountingassembly.
 31. A backflow preventer assembly comprising a housing havinga first end and a second end, the housing including a wall having aninner surface defining a through bore extending between the first endand the second end, a first mounting assembly including a wall having aninner surface defining a through bore in fluid communication with thehousing through bore adjacent the first end of the housing, the firstmounting assembly being configured to removably secure a first checkvalve thereto, a second mounting assembly including a wall having aninner surface defining a through bore in fluid communication with thehousing through bore adjacent the second end of the housing, the secondmounting assembly being configured to removably secure a second checkvalve thereto, a first coupling for securing the first mounting assemblyto the housing, the first coupling including a circumferential groove onthe first mounting assembly and a circumferential ridge at the first endof the housing wall, and a second coupling for securing the secondmounting assembly to the housing.
 32. The backflow preventer assembly ofclaim 31 wherein the second coupling comprises a circumferential grooveon the second mounting assembly and a circumferential ridge at thesecond end of the housing wall.